I have an HP Pavilion dv8. I installed Ubuntu 12.04 to replace Windows XP Home Edition and did an update to 12.04.1.

The connection to my Belkin router was fine during installation and did not disconnect.

After restarting for the update, the PC could not obtain an IP address, although it was seeing the router with good signal strength. The only solution I know of is to reboot the router, and then the connection is re-established.

This happens every time I shut down or restart. Packages are up to date.

Having done a search and reading somewhere about CA certs I am beginning to suspect that might be my problem?
I have since learned that there is an IP address conflict, windows 7 pc trying to connect to the router. It appears that when ubuntu connects to the router (after reboot of router) the ip address is RETAINED by the router after ubuntu pc is shut down.